Stacked heat exchanger

ABSTRACT

A stacked heat exchanger includes a first heat-exchanging portion in which heat is exchanged between a refrigerant and a coolant. The first heat-exchanging portion has multiple first plate members stacked and bonded to one another, and multiple first refrigerant channels and multiple coolant channels provided among the multiple first plate members. The multiple first refrigerant channels and the multiple coolant channels are arranged in a staking direction of the multiple first plate members. The stacked heat exchanger further includes a second ceiling board bonded to a first ceiling board which is one of the multiple first plate members located on an outermost side in the stacking direction, and a vapor-liquid separation portion having a space between the first ceiling board and the second ceiling board, separating the refrigerant flowed in into a vapor and a liquid, and storing an excess refrigerant in a refrigeration cycle.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Applications No. 2014-107117 filed on May 23, 2014, and No. 2014-221497 filed on Oct. 30, 2014.

TECHNICAL FIELD

The present disclosure relates to a stacked heat exchanger performing heat exchange between a refrigerant of a refrigeration cycle and a heat carrier.

BACKGROUND ART

A stacked heat exchanger in the related art is formed by stacking multiple heat-exchanger plates of substantially a flat plate shape at intervals so as to alternately form refrigerant channels and heat-carrier channels among the heat-exchanger plates and heat is exchanged between a refrigerant and a heat carrier. Such a stacked heat exchanger disclosed in Patent Document 1 integrally includes a cylindrical modulator, in which the refrigerant flowed out from the heat exchanger is separated into a vapor and a liquid and also the refrigerant is stored.

The stacked heat exchanger described in Patent Document 1, however, integrally includes the cylindrical modulator outside the heat exchanger shaped substantially like a case. Hence, a physical size is increased and an empty space called a dead space may possibly be formed when the heat exchanger is installed. Further, in a case where a subcooling portion to subcool a liquid-phase refrigerant flowed out from the modulator is added to the modulator-integrated heat exchanger as above, a physical size may be increased further.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: DE 102011078136 A1

SUMMARY

In view of the foregoing points, an object of the present disclosure is to reduce a physical size of a stacked heat exchanger including a vapor-liquid separation portion in which a refrigerant is separated into a vapor and a liquid and also to reduce a dead space formed where the stacked heat exchanger is installed.

According to an aspect of the present disclosure, a stacked heat exchanger includes a first heat-exchanging portion performing heat exchange between a refrigerant in a refrigeration cycle and a first heat carrier. The first heat-exchanging portion includes a plurality of first plate members stacked and bonded to one another, a plurality of first refrigerant channels through which the refrigerant flows, the plurality of first refrigerant channels being provided among the plurality of first plate members and arranged in a stacking direction of the plurality of first plate members to let the refrigerant flow, and a plurality of first heat carrier channels through which the first heat carrier flows, the plurality of first heat carrier channels being provided among the plurality of first plate members and arranged in the stacking direction of the plurality of first plate members. The stacked heat exchanger further includes a second end plate bonded to a first end plate which is one of the plurality of first plate members located on an outermost side in the stacking direction, and a vapor-liquid separation portion having a space provided between the first end plate and the second end plate, separating the refrigerant flowed therein into a vapor and a liquid, and storing an excess refrigerant in the refrigeration cycle.

According to the configuration as above, the second end plate is bonded to the first end plate so as to form a space in between and the space thus formed forms the vapor-liquid separation portion. Accordingly, the vapor-liquid separation portion can be provided by merely adding the second end plate of a plate shape to the first heat-exchanging portion. Hence, a size of the stacked heat exchanger can be reduced and a dead space formed where the stacked heat exchanger is installed can be also reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a heat exchanger according to a first embodiment of the present disclosure;

FIG. 2 is a view when a first ceiling board is viewed from a second ceiling board in the first embodiment;

FIG. 3 is a view when viewed from a direction indicated by an arrow III of FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3;

FIG. 5 is a sectional view showing a part of the heat exchanger of the first embodiment;

FIG. 6 is a perspective view of an offset fin of the first embodiment;

FIG. 7 is a side view of a heat exchanger according to a second embodiment of the present disclosure;

FIG. 8 is a schematic view of a heat exchanger according to a third embodiment of the present disclosure;

FIG. 9 is a view when viewed in a direction indicated by an arrow IX of FIG. 8;

FIG. 10 is a sectional view taken along the line X-X of FIG. 9;

FIG. 11 is a schematic view of a heat exchanger according to a fourth embodiment of the present disclosure;

FIG. 12 is a schematic view of a heat exchanger according to a fifth embodiment of the present disclosure;

FIG. 13 is a schematic view showing a flow of a refrigerant in a condensation mode of a heat exchanger according to a sixth embodiment of the present disclosure;

FIG. 14 is a view when viewed in a direction indicated by an arrow XIV of FIG. 13;

FIG. 15 is a sectional view taken along the line XV-XV of FIG. 14;

FIG. 16 is a sectional view taken along the line XVI-XVI of FIG. 14;

FIG. 17 is a sectional view taken along the line XVII-XVII of FIG. 14;

FIG. 18 is a schematic view showing a flow of the refrigerant in an evaporation mode of the heat exchanger of the sixth embodiment;

FIG. 19 is a schematic view showing a heat exchanger according to a seventh embodiment of the present disclosure;

FIG. 20 is a view when viewed from a direction indicated by an arrow XX of FIG. 20; and

FIG. 21 is a sectional view taken along the line XXI-XXI of FIG. 20.

DESCRIPTION OF EMBODIMENTS

Hereinafter, multiple embodiments for implementing the present invention will be described referring to drawings. In the respective embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.

First Embodiment

A first embodiment of the present disclosure will be described according to FIG. 1 through FIG. 6. A heat exchanger 10 shown in FIG. 1 forms a refrigeration cycle in a vehicle air-conditioning device. The heat exchanger 10 is a condenser to condense a high-pressure-side refrigerant in the refrigeration cycle by letting the high-pressure-side refrigerant and a coolant exchange heat. The coolant of the present embodiment corresponds to a first heat carrier of the present disclosure.

The coolant is, for example, a liquid or an antifreeze liquid containing at least ethylene glycol, dimethyl polysiloxane, or a nanofluid. In the present embodiment, an antifreeze liquid (LLC) based on ethylene glycol is used as the coolant.

The heat exchanger 10 includes a large number of first plate members 11 (hereinafter, referred to simply as the plate members 11) which are stacked and bonded to form a single integral unit. In the following, a stacking direction (up-down direction in a case of FIG. 1) of the plate members 11 is referred to as a plate stacking direction, one end side (upper end side in the case of FIG. 1) in the plate stacking direction is referred to as the first end side in the plate stacking direction, and the other end side (lower end side in the case of FIG. 1) is referred to as the second end side in the plate stacking direction.

Each plate member 11 is an elongated plate material of substantially a rectangular shape, and more specifically, made of a clad material, for example, an aluminum core cladded with brazing filler metal.

An overhanging portion 111 protruding substantially in the plate stacking direction (in other words, a direction substantially orthogonal to a plate surface of the plate member 11) is provided along an outer edge of the plate member 11 of substantially a rectangular shape. A large number of the plate members 11 are stacked one on another and the overhanging portions 111 are bonded together by brazing. A large number of the plate members 11 are disposed with protruding tip ends of the overhanging portions 111 faced in a same direction (substantially downward in the case of FIG. 1).

A large number of the plate members 11 form a first heat-exchanging portion 12 (hereinafter, referred to simply as the heat-exchanging portion 12), a first refrigerant tank space 13, a second refrigerant tank space 14, a first coolant tank space 15, and a second coolant tank space 16.

The heat-exchanging portion 12 includes multiple first refrigerant channels 121 (hereinafter, referred to simply as the refrigerant channels 121) and multiple first coolant channels 122 (hereinafter, referred to simply as the coolant channels 122). The coolant channels 122 of the present embodiment correspond to first heat carrier channels of the present disclosure.

The multiple refrigerant channels 121 and the multiple coolant channels 122 are provided among a large number of the plate members 11. A longitudinal direction of the refrigerant channels 121 and the coolant channels 122 coincides with a longitudinal direction of the plate members 11.

The refrigerant channels 121 and the coolant channels 122 are alternately stacked (disposed in parallel) one by one in the plate stacking direction. The plate members 11 serve as partition walls separating the refrigerant channels 121 from the coolant channels 122. Heat is exchanged between the refrigerant flowing in the refrigerant channels 121 and the coolant flowing in the coolant channels 122 through the plate members 11.

The first refrigerant tank space 13 and the first coolant tank space 15 are disposed to the heat-exchanging portion 12 on one side (right side in the case of FIG. 1) of the refrigerant channels 121 and the coolant channels 122, respectively. The second refrigerant tank space 14 and the second coolant tank space 16 are disposed to the heat-exchanging portion 12 on the other side (left side in the case of FIG. 1) of the refrigerant channels 121 and the coolant channels 122, respectively.

The first refrigerant tank space 13 and the second refrigerant tank space 14 are used to distribute and collect the refrigerant to and from the multiple refrigerant channels 121. The first coolant tank space 15 and the second coolant tank space 16 are used to distribute and collect the coolant to and from the multiple coolant channels 122.

The first refrigerant tank space 13, the second refrigerant tank space 14, the first coolant tank space 15, and the second coolant tank space 16 are formed of respective communication holes provided at four corners of the plate members 11. In the present embodiment, the first refrigerant tank space 13 and the second refrigerant tank space 14 are respectively provided at two diagonally opposite corners of the four corners of the plate members 11 of substantially a rectangular shape, and the first coolant tank space 15 and the second coolant tank space 16 are respectively provided at the remaining two corners.

One of a large number of the plate members 11 forming the heat-exchanging portion 12 located endmost on the first end side in the plate stacking direction is an endmost plate member 17, to which a first joint 21 and a first coolant pipe 22 are attached. The first joint 21 is a member to bond a refrigerant pipe and forms a refrigerant inlet 101 of the heat exchanger 10. The first coolant pipe 22 forms a coolant outlet 102 of the heat exchanger 10.

In the present embodiment, the first joint 21 is provided to the endmost plate member 17 on one end side (right side in the case of FIG. 1) in the longitudinal direction. The first coolant pipe 22 is provided to the endmost plate member 17 on the other end side (left side in the case of FIG. 1) in the longitudinal direction.

One of a large number of the plate members 11 forming the heat-exchanging portion 12 located endmost on the second end side in the plate stacking direction, that is, on an outermost side in the plate stacking direction is a first ceiling board 18 (first end plate). The overhanging portion 111 of the first ceiling board 18 extends longer in the plate stacking direction than the overhanging portions 111 of the other plate members 11. A plate second ceiling board 19 (second end plate) is bonded to the first ceiling board 18 by brazing so as to form a space in between. The space thus formed may be used as an example of a vapor-liquid separation portion 30 in which the refrigerant flowed inside is separated to a vapor and a liquid and also an excess refrigerant in the refrigeration cycle is stored.

As are shown in FIG. 2 and FIG. 4, a refrigerant inflow portion 181 is provided to the first ceiling board 18 in a lower portion in a direction of gravity to let the refrigerant flowing in the refrigerant channels 121 of the heat-exchanging portion 12 flow into the vapor-liquid separation portion 30. The refrigerant inflow portion 181 is a through-hole provided to the first ceiling board 18. To be more specific, the refrigerant inflow portion 181 is located below a liquid surface (see FIG. 2) of a liquid-phase refrigerant stored in the vapor-liquid separation portion 30 in the direction of gravity. Alternatively, the refrigerant inflow portion 181 may be provided to the first ceiling board 18 in a lower half region in the direction of gravity.

A first through-hole 182 in which to insert a first inner coolant pipe 41 described below is provided to the first ceiling board 18 on an upper side in the direction of gravity. To be more specific, the first through-hole 182 is located above a liquid surface of the liquid-phase refrigerant stored in the vapor-liquid separation portion 30 in the direction of gravity. In the present embodiment, both of the refrigerant inflow portion 181 and the first through-hole 182 are located on one end side (right side in a case of FIG. 2) of the first ceiling board 18 in the longitudinal direction.

As are shown in FIG. 3 and FIG. 4, a refrigerant outflow portion 191 is provided to the second ceiling board 19 in a lower portion in the direction of gravity to let the liquid-phase refrigerant flow out from the vapor-liquid separation portion 30 to an outside. The refrigerant outflow portion 191 is a through-hole provided to the second ceiling board 19. To be more specific, the refrigerant outflow portion 191 is located below a liquid surface of the liquid-phase refrigerant stored in the vapor-liquid separation portion 30 in the direction of gravity. Alternatively, the refrigerant outflow portion 191 may be provided to the second ceiling board 19 in a lower half region in the direction of gravity.

A second through-hole 192 in which to insert the first inner coolant pipe 41 described below is provided to the second ceiling board 19 on an upper side in the direction of gravity. An inner peripheral surface of the second through-hole 192 and an outer surface of the first inner coolant pipe 41 are bonded by brazing.

To be more specific, the second through-hole 192 is located above a liquid surface of the liquid-phase refrigerant stored in the vapor-liquid separation portion 30 in the direction of gravity. In the present embodiment, the second through-hole 192 is located on one end side (right side in a case of FIG. 3) of the second ceiling board 19 in the longitudinal direction. Meanwhile, the refrigerant outflow portion 191 is located on the other end side (left side in the case of FIG. 2) of the second ceiling board 19 in the longitudinal direction.

In the present embodiment, as is shown in FIG. 3, a protrusion 193 is provided to the second ceiling board 19 on the lower side in the direction of gravity to absorb stress applied to the second ceiling board 19 due to an increase in internal pressure of the vapor-liquid separation portion 30. By providing the protrusion 193, the vapor-liquid separation portion 30 can be made more rigid. In addition, a drying agent 31 is provided to the vapor-liquid separation portion 30 on the lower side in the direction of gravity to remove moisture in the liquid-phase refrigerant.

As are shown in FIG. 1 and FIG. 4, a second joint 23 and a second coolant pipe 24 are attached to the second ceiling board 19. The second joint 23 is a member to bond a refrigerant pipe and forms a refrigerant outlet 103 of the heat exchanger 10. The second coolant pipe 24 forms a coolant inlet 104 of the heat exchanger 10.

The refrigerant inlet 101 communicates with the first refrigerant tank space 13. The first refrigerant tank space 13 communicates with the vapor-liquid separation portion 30 through the refrigerant inflow portion 181. The vapor-liquid separation portion 30 communicates with the refrigerant outlet 103 through the refrigerant outflow portion 191.

As is shown in FIG. 4, a first inner coolant passage 40 is provided inside the vapor-liquid separation portion 30 to let the coolant flow and also allow the coolant inlet 104 and the first coolant tank space 15 to communicate. To be more specific, the first inner coolant pipe 41 which connects the second coolant pipe 24 and the first coolant tank space 15 is provided inside the vapor-liquid separation portion 30. The first inner coolant pipe 41 forms the first inner coolant passage 40.

Hence, as are shown in FIG. 1 and FIG. 4, the coolant inlet 104 communicates with the first coolant tank space 15 through the first inner coolant passage 40. Also, the coolant outlet 102 communicates with the second coolant tank space 16.

As is shown in FIG. 5, in the present embodiment, a large number of the plate members 11 forming the heat-exchanging portion 12 have protrusions 11 f of substantially a cylindrical shape protruding toward the first end side or the second end side in the plate stacking direction at four corners of the plate members 11. The protrusions 11 f form the first refrigerant tank space 13, the second refrigerant tank space 14, the first coolant tank space 15, and the second coolant tank space 16 separately.

One of a large number of the plate members 11 forming the heat-exchanging portion 12 located substantially at a center in the plate stacking direction is a center plate member 11A which has a closing portion 11 g closing the protrusion 11 f forming the first refrigerant tank space 13. The first refrigerant tank space 13 is thus divided into two spaces in the plate stacking direction. The closing portion 11 g is formed integrally with the protrusion 11 f, that is, the center plate member 11A.

Hence, as is indicated by solid arrows of FIG. 1, the refrigerant flowed into the first heat-exchanging portion 12 from the refrigerant inlet 101 flows into the vapor-liquid separation portion 30 from the refrigerant inflow portion 181 by flowing from the first refrigerant tank space 13 to the second refrigerant tank space 14 through the refrigerant channels 121 on the first end side in the plate stacking direction and subsequently flowing from the second refrigerant tank space 14 to the first refrigerant tank space 13 through the refrigerant channels 121 on the second end side in the plate stacking direction. In short, the heat exchanger 10 is configured to let the refrigerant flow by making a U-turn once. The refrigerant flowed into the vapor-liquid separation portion 30 is separated into a vapor and a liquid and a liquid-phase refrigerant flows out to the outside from the refrigerant outlet 103.

Also, as is indicated by alternate long and short dash arrows of FIG. 1, the coolant flowed into the first heat-exchanging portion 12 from the coolant inlet 104 flows out to the outside from the coolant outlet 102 by flowing from the first coolant tank space 15 to the second coolant tank space 16 through the coolant channels 122.

An offset fin 50 shown in FIG. 6 is disposed between the plate members 11. The offset fin 50 is an inner fin interposed between the plate members 11 to promote heat exchange between the refrigerant and the coolant.

The offset fin 50 is a plate-like member having rising portions 50 a formed by partially cutting and raising the plate-like member. A large number of the rising portions 50 a are provided in a direction F1 parallel to a flow direction of the refrigerant and the coolant (that is, the longitudinal direction of the plate members 11).

The rising portions 50 a aligned adjacently in the direction F1 parallel to the flow direction of the refrigerant and the coolant are offset from one another. In a case of FIG. 6, a large number of the rising portions 50 a are staggered in the direction F1 parallel to the flow direction of the refrigerant and the coolant. The offset fin 50 is bonded to both of the adjacent plate members 11 by brazing.

As has been described, in the heat exchanger 10 of the present embodiment, the second ceiling board 19 is bonded to the first ceiling board 18 so as to form a space in between and the space thus formed forms the vapor-liquid separation portion 30. Accordingly, the vapor-liquid separation portion 30 can be formed by merely adding the second ceiling board 19 of a plate shape to the first heat-exchanging portion 12. Hence, a size of the heat exchanger 10 integrally including the vapor-liquid separation portion 30 can be reduced and a dead space formed where the heat exchanger 10 is installed can be also reduced.

In addition, in the present embodiment, the refrigerant outflow portion 191 of the vapor-liquid separation portion 30 is located below a liquid surface of the liquid-phase refrigerant stored in the vapor-liquid separation portion 30 in the direction of gravity. The configuration as above can let the liquid-phase refrigerant flow out from the refrigerant outflow portion 191 in a reliable manner.

Second Embodiment

A second embodiment of the present disclosure will now be described according to FIG. 7. The second embodiment is different from the first embodiment above in that a heat exchanger 10 is installed in another direction.

As is shown in FIG. 7, the heat exchanger 10 of the present embodiment is installed in such a manner that a longitudinal direction of plate members 11, that is, a longitudinal direction of a first ceiling board 18 and a second ceiling board 19 coincides with a direction of gravity. Herein, a refrigerant inflow portion 181 and a refrigerant outflow portion 191 are located below a liquid surface (see FIG. 7) of a liquid-phase refrigerant stored in a vapor-liquid separation portion 30 in the direction of gravity.

A baffle plate 32 is disposed between the refrigerant inflow portion 181 and the refrigerant outflow portion 191 in the vapor-liquid separation portion 30. The baffle plate 32 divides an internal space of the vapor-liquid separation portion 30 on a lower side in the direction of gravity into a space which communicates with the refrigerant inflow portion 181 and a space which communicates with the refrigerant outflow portion 191. The baffle plate 32 is provided with multiple through-holes (not shown). Hence, the space which communicates with the refrigerant inflow portion 181 and the space which communicates with the refrigerant outflow portion 191 communicate with each other.

The baffle plate 32 extends in an upward direction substantially parallel to the direction of gravity from a lower end of the vapor-liquid separation portion 30 in the direction of gravity. In the present embodiment, an upper end of the baffle plate 32 in the direction of gravity is located below a liquid surface of the liquid-phase refrigerant stored in the vapor-liquid separation portion 30.

As has been described, the present embodiment is a case where the heat exchanger 10 is installed in such a manner that the longitudinal direction of the plate members 11 coincides with the direction of gravity, and the refrigerant outflow portion 191 of the vapor-liquid separation portion 30 is located below a liquid surface of the liquid-phase refrigerant stored in the vapor-liquid separation portion 30 in the direction of gravity. The configuration as above can let the liquid-phase refrigerant flow out from the refrigerant outflow portion 191 in a reliable manner.

In addition, vapor-liquid separation performance can be enhanced by providing the baffle plate 32 between the refrigerant inflow portion 181 and the refrigerant outflow portion 191 in the vapor-liquid separation portion 30. Further, the baffle plate 32 makes the vapor-liquid separation portion 30 more rigid.

Third Embodiment

A third embodiment of the present disclosure will now be described according to FIG. 8 through FIG. 10. The third embodiment is different from the first embodiment above in that a second heat-exchanging portion 62 is provided to a heat exchanger 10.

As is shown in FIG. 8, the second heat-exchanging portion 62 functioning as a subcooling portion in which a liquid-phase refrigerant flowed out from a vapor-liquid separation portion 30 is subcooled by letting the liquid-phase refrigerant and a low-pressure refrigerant in a refrigeration cycle exchange heat is connected to a second ceiling board 19 of the present embodiment. The low-pressure refrigerant of the present embodiment corresponds to a second heat carrier of the present disclosure.

The second heat-exchanging portion 62 includes multiple second plate members 61 which are stacked and bonded to one another to form a single integral unit. More specifically, a large number of the second plate members 61 form the second heat-exchanging portion 62, a first liquid-phase refrigerant tank space 63, a second liquid-phase refrigerant tank space 64, a first low-pressure refrigerant tank space 65, and a second low-pressure refrigerant tank space 66.

The second heat-exchanging portion 62 includes multiple second refrigerant channels 621 to let the liquid-phase refrigerant flow and multiple low-pressure refrigerant channels 622 to let the low-pressure refrigerant flow. The low-pressure refrigerant channels 622 of the present embodiment correspond to second heat carrier channels of the present disclosure.

The multiple second refrigerant channels 621 and the multiple low-pressure refrigerant channels 622 are provided among a large number of the second plate members 61. A longitudinal direction of the second refrigerant channels 621 and the low-pressure refrigerant channels 622 coincides with a longitudinal direction of the second plate members 61.

A length of the second plate members 61 in a flow direction of the liquid-phase refrigerant is shorter than a length of first plate members 11 in a flow direction of a refrigerant. In short, a length of the second plate members 61 in the longitudinal direction is shorter than a length of the first plate members 11 in the longitudinal direction. Also, a stacking direction of the second plate members 61 is parallel to a stacking direction of the first plate members 11.

The second refrigerant channels 621 and the low-pressure refrigerant channels 622 are alternately stacked (disposed in parallel) one by one in a plate stacking direction. The second plate members 61 serve as partition walls separating the second refrigerant channels 621 from the low-pressure refrigerant channels 622. Heat is exchanged between the refrigerant flowing in the second refrigerant channels 621 and the low-pressure refrigerant flowing in the low-pressure refrigerant channels 622 through the second plate members 61.

The first liquid-phase refrigerant tank space 63 and the first low-pressure refrigerant tank space 65 are disposed to the second heat-exchanging portion 62 on one side (right side in a case of FIG. 8) of the second refrigerant channels 621 and the low-pressure refrigerant channels 622, respectively. The second liquid-phase refrigerant tank space 64 and the second low-pressure refrigerant tank portion 66 are disposed to the second heat-exchanging portion 62 on the other side (left side in the case of FIG. 8) of the second refrigerant channels 621 and the low-pressure refrigerant channels 622, respectively.

The first liquid-phase refrigerant tank space 63 and the second liquid-phase refrigerant tank space 64 are used to distribute and collect the liquid-phase refrigerant to and from the multiple second refrigerant channels 621. The first low-pressure refrigerant tank space 65 and the second low-pressure refrigerant tank space 66 are used to distribute and collect the low-pressure refrigerant to and from the multiple low-pressure refrigerant channels 622.

The first liquid-phase refrigerant tank space 63, the second liquid-phase refrigerant tank space 64, the first low-pressure refrigerant tank space 65, and the second low-pressure refrigerant tank space 66 are formed of respective communication holes provided at four corners of the second plate members 61.

In the present embodiment, as is shown in FIG. 9, the first liquid-phase refrigerant tank space 63 and the second liquid-phase refrigerant tank space 64 are respectively provided at two diagonally opposite corners of the four corners of the second plate members 61 of substantially a rectangular shape. The first low-pressure refrigerant tank space 65 and the second low-pressure refrigerant tank space 66 are respectively provided at the remaining two corners of the second plate members 61.

As are shown in FIG. 8 and FIG. 10, one of a large number of the second plate members 61 forming the second heat-exchanging portion 62 located endmost on a first end side (upper side in the case of FIG. 8) in the plate stacking direction is a second endmost plate member 67 which is bonded to the second ceiling board 19 by brazing. The second endmost plate member 67 is provided with a liquid-phase refrigerant inflow hole 671 to let the liquid-phase refrigerant from the vapor-liquid separation portion 30 flow into the second heat-exchanging portion 62. The liquid-phase refrigerant inflow hole 671 is provided in a portion corresponding to a refrigerant outflow portion 191. Hence, the liquid-phase refrigerant in the vapor-liquid separation portion 30 flows into the second heat-exchanging portion 62 (to be more specific, the first liquid-phase refrigerant tank space 63) through the refrigerant outflow portion 191 and the liquid-phase refrigerant inflow hole 671.

As are shown in FIG. 8 and FIG. 9, one of a large number of the second plate members 61 forming the second heat-exchanging portion 62 located endmost on a second end side (lower side in the case of FIG. 8) in the plate stacking direction is a third endmost plate member 68, to which a second joint 23, a third joint 71, and a fourth joint 72 are attached. The third joint 71 is a member to bond a low-pressure refrigerant pipe and forms a low-pressure refrigerant inlet 701 of the second heat-exchanging portion 62. The low-pressure refrigerant inlet 701 may be connected to a low-pressure side of a refrigeration cycle to let the low-pressure refrigerant in the refrigeration cycle flow into the low-pressure refrigerant inlet 701. The low-pressure refrigerant flowing into the second heat-exchanging portion 62 is at a pressure lower than a pressure of the refrigerant flowing into a first heat-exchanging portion 12. The fourth joint 72 is a member to bond a low-pressure refrigerant pipe and forms a low-pressure refrigerant outlet 702 of the second heat-exchanging portion 62.

In the present embodiment, the fourth joint 72 is provided to the third endmost plate member 68 on one end side (right side in a case of FIG. 9) in the longitudinal direction. The second joint 23 and the third joint 71 are provided to the third endmost plate member 68 on the other end side (left side in the case of FIG. 9) in the longitudinal direction. In addition, the second joint 23 is provided above the third joint 71 in a direction of gravity.

Flows of the liquid-phase refrigerant and the low-pressure refrigerant in the second heat-exchanging portion 62 of the present embodiment will now be described.

As is indicated by solid arrows of FIG. 8, the refrigerant flowed into the second heat-exchanging portion 62 from the vapor-liquid separation portion 30 flows out to an outside from a refrigerant outlet 103 by flowing from the first liquid-phase refrigerant tank space 63 to the second liquid-phase refrigerant tank space 64 through the second refrigerant channels 621. As is indicated by dotted arrows of FIG. 8, the low-pressure refrigerant flowed into the second heat-exchanging portion 62 from the low-pressure refrigerant inlet 701 flows out to the outside from the low-pressure refrigerant outlet 702 by flowing from the second low-pressure refrigerant tank space 66 to the first low-pressure refrigerant tank space 65 through the low-pressure refrigerant channels 622.

As has been described, in the present embodiment, the second heat-exchanging portion 62 functioning as the subcooling portion is connected to the second ceiling board 19 of the heat exchanger 10. Owing to the configuration as above, the vapor-liquid separation portion 30 can be more rigid.

Also, in the present embodiment, a length of the second plate members 61 in a flow direction of the liquid-phase refrigerant is shorter than a length of the first plate members 11 in a flow direction of the refrigerant. When configured as above, a space is formed in the second heat-exchanging portion 62 on one end side (right side in the case of FIG. 8) in the flow direction of the refrigerant. The space thus formed can be effectively used as an installation space of a second coolant pipe 24. Consequently, a dead space formed where the heat exchanger 10 is installed can be reduced.

Incidentally, a fin-tube heat exchanger as a comparative example cools a refrigerant by letting a refrigerant flowing inside tubes and cooling air flowing outside the tubes exchange heat, and includes a vapor-liquid separation portion between a condensation portion (corresponding to the first heat-exchanging portion 12 of the present embodiment) in a heat dissipation core and a subcooling portion (corresponding to the second heat-exchanging portion 62 of the present embodiment). In the heat exchanger of the comparative example, the vapor-liquid separation portion is set at a position where the vapor-liquid separation portion is constantly hit by cooling air (running-induced air current). Hence, a state of the refrigerant in the vapor-liquid separation portion may possibly vary with a temperature of the cooling air.

Contrary to the comparative example above, the heat exchanger 10 of the present embodiment is a water-cooled stacked heat exchanger. Hence, a running-induced air current does not hit the vapor-liquid separation portion 30. Consequently, a state variation of the refrigerant in the vapor-liquid separation portion 30 can be restricted.

In the heat exchanger of the comparative example, the vapor-liquid separation portion is disposed between the condensation portion and the subcooling portion in a low-rigid fin-tube heat exchanger. Hence, rigidity of the vapor-liquid separation portion needs to be increased. Accordingly, the vapor-liquid separation portion has to be formed of an extruded tube or the like formed by extrusion molding. Such an extruded tube, however, increases manufacturing costs.

In contrast, in the heat exchanger 10 of the present embodiment, the vapor-liquid separation portion 30 can be formed of two plate members, namely the first ceiling board 18 and the second ceiling board 19. Hence, the manufacturing costs can be reduced.

Fourth Embodiment

A fourth embodiment of the present disclosure will now be described according to FIG. 11. The fourth embodiment is different from the third embodiment above in that a second heat-exchanging portion 62 is a subcooling portion in which a liquid-phase refrigerant is subcooled by letting the liquid-phase refrigerant and a coolant exchange heat. The coolant of the present embodiment corresponds to a second heat carrier of the present disclosure.

As is shown in FIG. 11, in the present embodiment, a large number of second plate members 61 form the second heat-exchanging portion 62, a first liquid-phase refrigerant tank space 63, a second liquid-phase refrigerant tank space 64, a third coolant tank space 650, and a fourth coolant tank space 660.

The second heat-exchanging portion 62 includes multiple second refrigerant channels 621 to let the liquid-phase refrigerant flow and multiple second coolant channels 623 to let the coolant flow. The second coolant channels 623 of the present embodiment correspond to second heat carrier channels of the present disclosure.

The multiple second refrigerant channels 621 and the multiple second coolant channels 623 are provided among a large number of the second plate members 61. A longitudinal direction of the second refrigerant channels 621 and the second coolant channels 623 coincides with a longitudinal direction of the second plate member 61.

The second refrigerant channels 621 and the second coolant channels 623 are alternately stacked (disposed in parallel) one by one in a plate stacking direction. The second plate members 61 serve as partition walls separating the second refrigerant channels 621 from the second coolant channels 623. Heat is exchanged between the refrigerant flowing in the second refrigerant channels 621 and the coolant flowing in the second coolant channels 623 through the second plate members 61.

The first liquid-phase refrigerant tank space 63 and the third coolant tank space 650 are disposed to the second heat-exchanging portion 62 on one end side (right side in a case of FIG. 11) of the second refrigerant channels 621 and the second coolant channels 623, respectively. The second liquid-phase refrigerant tank space 64 and the fourth coolant tank space 660 are disposed to the second heat-exchanging portion 62 on the other end side (left side in the case of FIG. 11) of the second refrigerant channels 621 and the second coolant channels 623, respectively. The third coolant tank space 650 and the fourth coolant tank space 660 are used to distribute and collect the coolant to and from the multiple second coolant channels 623.

The first liquid-phase refrigerant tank space 63, the second liquid-phase refrigerant tank space 64, the third coolant tank space 650, and the fourth coolant tank space 660 are formed of respective communication holes provided at four corners of the second plate members 61. In the present embodiment, the third coolant tank space 650 and the fourth coolant tank space 660 are provided at two diagonally opposite corners of the four corners of the second plate members 61 of substantially a rectangular shape.

A second endmost plate member 67 is provided with a through-hole (not shown) in which to insert a second inner coolant pipe 81 described below. The through-hole is bonded to an outer surface of the second inner coolant pipe 81 by brazing. Also, the through-hole is provided to the second endmost plate member 67 at an end opposite to a liquid-phase refrigerant inflow hole 671 in the longitudinal direction.

A second joint 23 and a third coolant pipe 73 are attached to a third endmost plate member 68. The third coolant pipe 73 forms a coolant inlet 703 of the second heat-exchanging portion 62.

In the present embodiment, the third coolant pipe 73 is provided to the third endmost plate member 68 on one end side (right side in the case of FIG. 11) in the longitudinal direction. The second joint 23 is provided to the third endmost plate member 68 on the other end side (left side in the case of FIG. 8) in the longitudinal direction.

A second inner coolant passage 80 is provided inside a vapor-liquid separation portion 30 to let the coolant flow and allow the fourth coolant tank space 660 and a second coolant tank space 16 to communicate. To be more specific, the second inner coolant pipe 81 connecting the fourth coolant tank space 660 and the second coolant tank space 16 is provided inside the vapor-liquid separation portion 30. The second inner coolant pipe 81 forms the second inner coolant passage 80.

In the present embodiment, a large number of first plate members 11 of a first heat-exchanging portion 12 located between a first ceiling board 18 and a substantial center in the plate stacking direction has a first closing portion (not shown) closing a protrusion (not shown) forming a first coolant tank space 15. The first coolant tank space 15 is thus divided into two spaces in the plate stacking direction.

A large number of the first plate members 11 of the first heat-exchanging portion 12 located between substantially the center in the plate stacking direction and an endmost plate member 17 has a second closing portion (not shown) closing a protrusion (not shown) forming the second coolant tank space 16. The second coolant tank space 16 is thus divided into two spaces in the plate stacking direction.

A flow of the coolant in a heat exchanger 10 of the present embodiment will now be described.

As is indicated by alternate long and short dash arrows of FIG. 11, the coolant flowed into the third coolant tank space 650 from the coolant inlet 703 of the second heat-exchanging portion 62 flows into the fourth coolant tank space 660 by flowing in the coolant channels 623. The coolant flowed into the fourth coolant tank space 660 flows into the second coolant tank space 16 of the first heat-exchanging portion 12 by flowing in the second inner coolant passage 80.

Meanwhile, the coolant flowed into the first coolant tank space 15 from the coolant inlet 104 of the heat exchanger 10 through the first inner coolant passage 40 flows into the second coolant tank space 16 by flowing in first coolant channels 122 on a second end side (lower side in the case of FIG. 11) in the plate stacking direction. Hence, the heat exchanger 10 of the present embodiment is configured so as to let the coolant flowed into the first heat-exchanging portion 12 from the coolant inlet 104 of the heat exchanger 10 and the coolant which has passed through the second heat-exchanging portion 62 merge in the second coolant tank space 16.

The coolant flowed into the second coolant tank space 16 flows out to an outside from a coolant outlet 102 by flowing from the second coolant tank space 16 to the first coolant tank space 15 through the first coolant channels 122 at or near the center in the plate stacking direction and subsequently flowing from the first coolant tank space 15 to the second coolant tank space 16 through the first coolant channels 122 on a first end side (upper side in the case of FIG. 11) in the plate stacking direction. In short, the first heat-exchanging portion 12 is configured to let the coolant flow by making a U-turn twice.

As has been described, the heat exchanger 10 of the present embodiment is configured so as to let both the coolant flowing from the coolant inlet 104 of the heat exchanger 10 and the coolant which has passed through the second heat-exchanging portion 62 flow into the first heat-exchanging portion 12. In short, the configuration as above can let two streams of the coolant flow into the first heat-exchanging portion 12 in parallel. Consequently, a pressure loss of the coolant in the first heat-exchanging portion 12 can be reduced. Hence, heat-exchanging efficiency of the first heat-exchanging portion 12 can be enhanced.

Fifth Embodiment

A fifth embodiment of the present disclosure will now be described according to FIG. 12. The fifth embodiment is different from the fourth embodiment above in that the coolant inlet 104 and the first inner coolant pipe 41 are omitted to let a coolant which has passed through a second heat-exchanging portion 62 and a refrigerant exchange heat in a first heat-exchanging portion 12.

As is shown in FIG. 12, a second coolant tank space 16 in the first heat-exchanging portion 12 is formed to let only a coolant which has passed through the second heat-exchanging portion 62 flow inside. Also, in the present embodiment, of a large number of first plate members 11 forming the first heat-exchanging portion 12, a center plate member 11A has a closing portion (not shown) closing a protrusion (not shown) forming the second coolant tank space 16. The second coolant tank space 16 is thus divided into two spaces in a plate stacking direction.

Hence, the coolant flowed into the second coolant tank space 16 flows out to an outside from a coolant outlet 102 by flowing from the second coolant tank space 16 to a first coolant tank space 15 through first coolant channels 122 on a second end side (lower side in a case of FIG. 12) in the plate stacking direction and subsequently flowing from the first coolant tank space 15 to the second coolant tank space 16 through the first coolant channels 122 on a first end side (upper side in the case of FIG. 11) in the plate stacking direction. In short, the first heat-exchanging portion 12 is configured to let the coolant flow by making a U-turn once.

As has been described, a heat exchanger 10 of the present embodiment is configured so as to let the coolant which has passed through the second heat-exchanging portion 62 flow into the first heat-exchanging portion 12. That is to say, the configuration as above lets a whole amount of coolant which flows into the heat exchanger 10 pass through the second heat-exchanging portion 62. Hence, a liquid-phase refrigerant separated from a vapor in a vapor-liquid separation portion 30 can be subcooled preferentially.

Herein, a refrigerant is cooled in the first heat-exchanging portion 12 by the coolant which has passed through the second heat-exchanging portion 62. It should be appreciated, however, that deterioration of a refrigerant condensation function of the first heat-exchanging portion 12 can be restricted because a cooling capability required to subcool the liquid-phase refrigerant is low.

Sixth Embodiment

A sixth embodiment of the present disclosure will now be described according to FIG. 13 through FIG. 18. The fifth embodiment is different from the fifth embodiment above in that a heat exchanger 10 is used as an outdoor unit of a heat pump cycle capable of switching from a condensation mode to an evaporation mode and vice versa.

The condensation mode is a mode in which the heat exchanger 10 functions as a condenser to condense a high-pressure-side refrigerant in a refrigeration cycle by letting the high-pressure-side refrigerant and a coolant exchange heat. The evaporation mode is a mode in which the heat exchanger 10 functions as an evaporator to turn a low-pressure-side refrigerant in the refrigeration cycle into a vapor by letting the low-pressure-side refrigerant and the coolant exchange heat. In FIG. 13 through FIG. 18, solid arrows indicate a flow of the refrigerant in the condensation mode, alternate long and two short dashes arrows indicate a flow of the refrigerant in the evaporation mode, and alternate long and short dash arrows indicate a flow of the coolant.

As are shown in FIG. 13 and FIG. 17, a second joint 23 of the present embodiment forms a first refrigerant outlet 103 to let the refrigerant flow out from a second heat-exchanging portion 62 to an outside in the condensation mode. As are shown in FIG. 14 and FIG. 17, the second joint 23 is provided to a third endmost plate member 68 on an upper side in a direction of gravity. In the present embodiment, as is shown in FIG. 16, a third coolant pipe 73 is also provided to the third endmost plate member 68 on the upper side in the direction of gravity.

As are shown in FIG. 14 and FIG. 15, a fifth joint 75 is attached to a second ceiling board 19 at an end in a longitudinal direction near a refrigerant inflow portion 181. The fifth joint 75 is a member to bond a refrigerant pipe and forms a second refrigerant outlet 705 to let the refrigerant flow out from a vapor-liquid separation portion 30 to the outside in the evaporation mode. In the present embodiment, the refrigerant inflow portion 181 and the fifth joint 75 are provided to the second ceiling board 19 on the upper side in the direction of gravity.

A flow of the refrigerant in the heat exchanger 10 of the present embodiment will now be described.

In the condensation mode, as indicated by the sold arrows of FIG. 13, the refrigerant flowed into the vapor-liquid separation portion 30 from the refrigerant inflow portion 181 is separated into a vapor and a liquid in the vapor-liquid separation portion 30. A liquid-phase refrigerant separated from a vapor in the vapor-liquid separation portion 30 flows into a first liquid-phase refrigerant tank space 63 from a liquid-phase refrigerant inflow hole 671. The refrigerant flowed into the first liquid-phase refrigerant tank space 63 flows out to the outside from the refrigerant outlet 103 by flowing from the first liquid-phase refrigerant tank space 63 to a second liquid-phase refrigerant tank space 64 through second refrigerant channels 621.

Meanwhile, in the evaporation mode, as indicated by the alternate long and two dashes arrows of FIG. 18, the refrigerant flowed into the vapor-liquid separation portion 30 from the refrigerant inflow portion 181 flows out to the outside from the second refrigerant outlet 705.

Hence, the vapor-liquid separation portion 30 has a refrigerant passage to let the refrigerant flowed inside from a first heat-exchanging portion 12 in the condensation mode flow out to the second heat-exchanging portion 62 and another refrigerant passage to let the refrigerant flowed inside from the first heat-exchanging portion 12 in the evaporation mode flow out to the outside.

Refrigerant channels inside the heat exchanger 10 can be switched by a valve or the like provided outside the heat exchanger 10 (to be more specific, on a refrigerant outlet side). By switching the refrigerant channels inside the heat exchanger 10 as above, the evaporation mode and the condensation mode can be switched from each other.

As has been described, the heat exchanger 10 of the present embodiment is capable of forming a refrigerant flow in the condensation mode and a refrigerant flow in the evaporation mode inside the heat exchanger 10. Hence, the heat exchanger 10 of the present embodiment can be used suitably as an outdoor unit of a heat pump cycle. In such a case, the outdoor unit can be water-cooled outdoor unit. Consequently, COP control can be performed easily because a refrigerant behavior is stabilized by a heat accumulation effect of the coolant.

Seventh Embodiment

A seventh embodiment of the present disclosure will now be described according to FIG. 19 through FIG. 21. The seventh embodiment is different from the fourth embodiment above in a configuration of a vapor-liquid separation portion 30.

As are shown in FIG. 19 and FIG. 20, the vapor-liquid separation portion 30 of the present embodiment includes multiple third plate members 91 which are stacked and bonded to one another to form a single integral unit. A stacking direction of the third plate members 91 is parallel to a stacking direction (plate stacking direction) of first plate members 11. The third plate members 91 and the first plate members 11 have an equal length in an installation direction and an equal length in a width direction.

A large number of the third plate members 91 are disposed with protruding tip ends of overhanging portions 911 faced in a same direction. In the present embodiment, the first plate members 11 are disposed with protruding tip ends of overhanging portions 111 faced to an opposite side (upward in a case of FIG. 19) to the vapor-liquid separation portion 30. On the other hand, second plate members 61 and the third plate members 91 are disposed with protruding tip ends of corresponding overhanging portions 611 and 911 faced to an opposite side (downward in the case of FIG. 19) to a first heat-exchanging portion 12.

As is shown in FIG. 21, multiple vapor-liquid separation passages 92 are provided among the multiple third plate members 91 to let a refrigerant flowed inside from first refrigerant channels 121 of the first heat-exchanging portion 12 flow. The third plate members 91 are provided with first through-holes 912. Hence, every two adjacent vapor-liquid separation passages 92 communicate with each other. An inner fin is not disposed to the vapor-liquid separation channels 92.

One of a large number of the third plate members 91 of the vapor-liquid separation portion 30 located endmost on a first end side in the plate stacking direction is referred to as a third ceiling board 93 (third end plate) and one located endmost on a second end side in the plate stacking direction is referred to as a fourth ceiling board 94 (fourth end plate).

The third ceiling board 93 is bonded to a first ceiling board 18 on a surface on the second end side in the plate stacking direction. A second ceiling board 19 is bonded to the fourth ceiling board 94 on a surface of the overhanging portion 911 on the second end side in the plate stacking direction. In addition, the third ceiling board 93 is thicker than the other third plate members 91.

The third plate members 91 are provided with second through-holes 913 to let a first inner coolant pipe 41 penetrate through and third through-holes (not shown) to let a second inner coolant pipe 81 penetrate through. In the present embodiment, the first inner coolant pipe 41 is formed integrally with a second coolant pipe 24.

As are shown in FIG. 20 and FIG. 21, an insertion opening 96 from which to insert a drying agent 95 into the vapor-liquid separation portion 30 is provided to the second ceiling board 19 in a portion other than where a second heat-exchanging portion 62 is bonded. The insertion opening 96 is closed by a stopper portion 97.

The drying agent 95 is a packet of zeolite particles for water absorption and absorbs moisture in the refrigerant. The drying agent 95 is used in order to prevent moisture in the refrigerant from giving rise to corrosion of respective functional parts forming a refrigeration cycle or from blocking a flow of the refrigerant by freezing in fine pores of an expansion valve.

The drying agent 95 is disposed inside the vapor-liquid separation portion 30, that is, in the vapor-liquid separation passage 92 at a portion corresponding to the insertion opening 96. In the present embodiment, the drying agent 95 is disposed in close proximity to the first through-holes 912.

Although it is not shown in the drawings, the third ceiling board 93 of the present embodiment is provided with a recessed portion. The recessed portion is provided by making a dent toward the second end side in the plate stacking direction in a part of the third ceiling board 93. By providing the recessed portion to the third ceiling board 93, a clearance can be provided between the first ceiling board 18 and the third ceiling board 93, that is, between the first heat-exchanging portion 12 and the vapor-liquid separation portion 30.

As has been described, in the present embodiment, a vapor-liquid separation space in the vapor-liquid separation portion 30 is formed of a large number of the third plate members 91. A refrigerant liquid surface is thus divided in the vapor-liquid separation portion 30. Hence, bubbling of the refrigerant liquid surface can be restricted.

Given that a length of the second plate members 61 in a refrigerant flow direction is equal to a length of the first plate members 11 in the refrigerant flow direction, then a special part is additionally required to set the drying agent 95 inside the vapor-liquid separation portion 30 and adding a special part raises a problem that manufacturing costs are increased.

On the contrary, a length of the second plate members 61 in a refrigerant flow direction is made shorter than a length of the first plate members 11 in the refrigerant flow direction in the present embodiment. Further, the insertion opening 96 from which the drying agent 95 is inserted into the vapor-liquid separation portion 30 is provided to the second ceiling board 19 in a portion other than where the second heat-exchanging portion 62 is bonded. When configured in the manner as above, the drying agent 95 can be inserted into the vapor-liquid separation portion 30 without having to add a special part to set the drying agent 95.

In the present embodiment, offset fins 50 are disposed to the first refrigerant channels 121. Hence, the refrigerant is prevented from flowing into the vapor-liquid separation portion 30 in the form of two separate phases (gas phase and liquid phase). Because the third plate members 91 are cooled by the liquid-phase refrigerant in the vapor-liquid separation portion 30, even when a slight amount of air bubbles (gas-phase refrigerant) are mixed in the refrigerant when the refrigerant flows into the vapor-liquid separation portion 30, the air bubbles are cooled and condensed by exchanging heat with the third plate members 91.

Hence, in the present embodiment, vapor-liquid separation performance in the vapor-liquid separation portion 30 can be enhanced.

In the present embodiment, a clearance is provided between the first heat-exchanging portion 12 and the vapor-liquid separation portion 30 by providing the recessed portion in the third ceiling board 93. Consequently, heating of the liquid-phase refrigerant in the vapor-liquid separation portion 30 by heat of the hot refrigerant can be restricted.

In the present embodiment, it is configured so as to let the coolant cooled in an unillustrated radiator flow into the first heat-exchanging portion 12 from a coolant inlet 104 through a first inner coolant passage 40 and also into the second heat-exchanging portion 62 from a coolant inlet 703. Hence, by controlling an amount of the coolant flowing into the first and second heat-exchanging portions 12 and 62 from the two coolant inlets 104 and 703, respectively, distribution of flow rates, that is, a flow rate of passing coolant to the first heat-exchanging portion 12 and a flow rate of passing coolant to the second heat-exchanging portion 62, can be controlled.

In other words, when a flow rate of passing coolant to the first heat-exchanging portion 12 is increased, condensation capability of the refrigerant can be increased by enhancing condensation performance. On the other hand, when a flow rate of passing coolant to the second heat-exchanging portion 62 is increased, a subcooling degree of the refrigerant can be increased by enhancing subcooling performance of the refrigerant.

Alternatively, a special radiator to cool the coolant heated in the second heat-exchanging portion 62 may be provided to let the coolant cooled in the special radiator flow into the second heat-exchanging portion 62. When configured in such a manner, a subcooling degree of the refrigerant can be increased further.

In the case of an air-cooled heat exchanger configured to cool a refrigerant by letting the refrigerant and air exchange heat, when a condensation portion and a subcooling portion are disposed on a same heat dissipation surface, an amount of air flowing into the heat exchanger may not be controlled. Herein, a subcooling degree of the refrigerant is increased only by changing a ratio of heat dissipation areas between the condensation portion and the subcooling portion. That is, an area of the subcooling portion is increased whereas an area of the condensation portion is decreased. However, when an area of the condensation portion is decreased, a refrigerant pressure is increased and it becomes practically difficult to control a subcooling degree of the refrigerant.

On the contrary, a subcooling degree of the refrigerant can be controlled in the present embodiment by performing the flow-rate distribution control on a flow rate of passing coolant to the first heat-exchanging portion 12 and a flow rate of passing coolant to the second heat-exchanging portion 62.

It should be appreciated that the present disclosure is not limited to the embodiments described above and can be modified in various manners within the scope of the present disclosure.

The sixth embodiment above has described a case where the refrigerant channels in the heat exchanger 10 are switched by a valve or the like provided outside of the heat exchanger 10. However, the switching method of the refrigerant channels is not limited to the method described above. For example, a valve or the like capable of switching two refrigerant flows, that is, a refrigerant flow to let the refrigerant flowed out from the first heat-exchanging portion 12 flow to an outside and a refrigerant flow to let the refrigerant flowed out from the first heat-exchanging portion 12 flow into the second heat-exchanging portion 62, may be provided inside the vapor-liquid separation portion 30 of the heat exchanger 10.

Means disclosed in the respective embodiments above may be combined as needed within a feasible range. 

What is claimed is:
 1. A stacked heat exchanger, comprising: a first heat-exchanging portion performing heat exchange between a refrigerant in a refrigeration cycle and a first heat carrier, wherein the first heat-exchanging portion includes: a plurality of first plate members stacked and bonded to one another; a plurality of first refrigerant channels through which the refrigerant flows, the plurality of first refrigerant channels being provided among the plurality of first plate members and arranged in a stacking direction of the plurality of first plate members to let the refrigerant flow; and a plurality of first heat carrier channels through which the first heat carrier flows, the plurality of first heat carrier channels being provided among the plurality of first plate members and arranged in the stacking direction of the plurality of first plate members; a second end plate arranged such that a space is provided between the second end plate and a first end plate which is one of the plurality of first plate members located on an outermost side in the stacking direction; a vapor-liquid separation portion having the space provided between the first end plate and the second end plate, separating the refrigerant flowed therein into a vapor and a liquid, and storing an excess refrigerant in the refrigeration cycle; and a second heat-exchanging portion performing heat exchange between the refrigerant and a second heat carrier, wherein: the second heat-exchanging portion includes: a plurality of second plate members stacked and bonded to one another; a plurality of second refrigerant channels through which the refrigerant flows, the plurality of second refrigerant channels being provided among the plurality of second plate members; and a plurality of second heat carrier channels through which the second heat carrier flows, the plurality of second refrigerant channels being provided among the plurality of second plate members, wherein a length of the plurality of second plate members in a flow direction of the refrigerant is shorter than a length of the plurality of first plate members in the flow direction of the refrigerant, the second heat-exchanging portion is bonded to the second end plate, and the second refrigerant channels communicate with the vapor-liquid separation portion.
 2. The stacked heat exchanger according to claim 1, wherein: a lower portion of the first end plate in a direction of gravity has a refrigerant inflow portion through which the refrigerant flows into the vapor-liquid separation portion; and a lower portion of the second end plate in a direction of gravity has a refrigerant outflow portion through which the refrigerant in a liquid phase flow out from the vapor-liquid separation portion.
 3. (canceled)
 4. The stacked heat exchanger according to claim 1, wherein each of the first heat carrier and the second heat carrier is a coolant, and the stacked heat exchanger further comprising an inner coolant passage provided inside the vapor-liquid separation portion, wherein the coolant flows through the inner coolant passage, and the first heat carrier channels and the second heat carrier channels communicate with each other through the inner coolant passage.
 5. The stacked heat exchanger according to claim 1, wherein the second heat carrier is a low-pressure refrigerant that is lower in pressure than the refrigerant flowing into the first heat-exchanging portion.
 6. The stacked heat exchanger according to claim 1, wherein the vapor-liquid separation portion includes therein a refrigerant passage through which the refrigerant flowed in from the first heat-exchanging portion flows out to an outside, and a refrigerant passage through which the refrigerant flowed in from the first heat-exchanging portion flows out to the second heat-exchanging portion.
 7. The stacked heat exchanger according to claim 1, wherein: the vapor-liquid separation portion includes a plurality of third plate members disposed in the space between the first end plate and the second end plate and stacked and bonded to one another, and a plurality of vapor-liquid separation passages being provided among the plurality of third plate members, separating the refrigerant into a vapor and a liquid and storing an excess refrigerant in the refrigeration cycle is stored; and the vapor-liquid separation passages adjacent to each other communicate with each other.
 8. The stacked heat exchanger according to claim 1, wherein the second end plate has an insertion opening for insertion of a drying agent into the vapor-liquid separation portion in an area other than where the second heat-exchanging portion is bonded. 